| Abstract: | The location of transverse bands within the major repeating period of positively stained collagen fibrils was determined from electron micrographs by an optical averaging procedure. From these data and the published location of bands in SLS crystallites, we have prepared a two-dimensional representation, accurate to about 25 Å, of the modified quarter-stagger arrangement of molecules in the collagen fibril. With this information it is possible to demonstrate the relationship of loci on individual collagen molecules within the fibril. For example, the site where the collagen molecule is cleaved by tadpole collagenase, the site where a disaccharide unit is covalently bound to the α1-CB5 peptide, and the site of carboxyl-terminal intermolecular cross-linking all occur in the fibril near the amino-terminal edge of the “hole zone;” and the site of amino-terminal cross-linking occurs near the carboxyl-terminal edge of the “hole zone.” |
